It's got history! That's really unusual for moves to open-source; the dates on the earliest commits are in 1990 and they do go forward in time so that's really unusual to have that much history. I bet there's some fun stuff in there.
1,491 karma · joined December 25, 2017
Good to see it's getting some modern support.
See p.14 of https://stacks.stanford.edu/file/cv716pj4036/Technical%20Rep...
Not sure if the principal is similar or not. (There was one down at the Bletchley computing museum many years ago when I went down)